1.7.1 Gear Train and Timing
DETROIT DIESEL 53
the idler gear bearing.
The gear train is lubricated by the overflow of oil
from the camshaft and balance shaft pockets spilling
into the gear train compartment A certain amount of
the oil also spills into the gear train compartment
from the camshaft and balance shaft end bearings and
The correct relationship between the crankshaft and
spindle movement of at least I". Provide an extension
for the indicator spindle. The extension must be long
camshaft(s) must he maintained to properly control
fuel injection end the opening and closing of the
enough to contact the piston just before it reaches the
end of its upward stroke. Also. select suitable
mounting attachments for the indicator so it can be
The crankshaft timing gear can he mounted in only
mounted over the injector tube in the cylinder head.
one position since it is keyed to the crankshaft. The
camshaft gear(s) can also he mounted in only one
6. Mount the indicator over the injector tube. Check to
position due to the location of the keyway relative to
he sure the indicator spindle extension is free in the
the cams. Therefore, when the engine is properly
injector tube and is free to travel at least one inch.
timed. the markings on the various gears will match as
shown in Fig 1.
7. Attach a suitable pointer to the engine lower front
cover. The outer end of the pointer should extend out
Pre-ignition. uneven running and a loss of power may
over the top of the crankshaft pulley.
result if an engine is "out of time".
When an engine is suspected of being out of time, due
8. Turn the crankshaft slowly, in the direction of
IO an improperly assembled gear train. a quick check
engine rotation, until the indicator hand just stops
can he made without removing the flywheel and
flywheel housing by following the procedure outlined
9. Continue IO turn the crankshaft, in the direction of
rotation, until the indicator starts to move again . Now
set the indicator on zero and continue to turn the
Chock Engine liming
crankshaft until the indicator reading is .010"
Access to the crankshaft pulley. to mark the top dead
center position of the selected piston. and to the front
end of the crankshaft or the flywheel for turning the
crankshaft is necessary when performing the timing
check. Then, proceed as follows:
1. Clean and remove the valve rocker cover.
2. Select any cylinder for the timing check.
3. Remove the injector as outlined in Section 2.1 or
4. Carefully slide a rod. approximately 12" long,
through the injector tube until the end of the rod rests
on top of the piston. Place the throttle in the no-fuel
* Indicator readings shown ore nominal valuer. The
position. Then, turn the crankshaft slowly in the
allowable tolerance is ± .005 in.
direction of engine rotation. Stop when the rod
(1) High velocity type injector corn.
reaches the end of its upward travel. Remove the rod
(2) Low velocity type injector cam.
and turn the crankshaft, opposite the direction of
rotation, between 1/16 and 1/8 of a turn.
5. Select a dial indicator with .001" graduations and a